In the fields of chemistry, biology, materials science, microelectronics, optics, and medicine the development of devices which are small relative to the state of the art and which are conveniently and relatively inexpensively produced is important.
A well-known method of production of devices, especially in the area of microelectronics, is photolithography. According to this technique, a negative or positive resist (photoresist) is coated onto an exposed surface of an article. The resist then is irradiated in a predetermined pattern, and portions of the resist that are irradiated (positive resist) or nonirradiated (negative resist) are removed from the surface to produce a predetermined pattern of resist on the surface. This is followed by one or more procedures. According to one, the resist serves as a mask in an etching process in which areas of the material not covered by the resist are chemically removed, followed by removal of resist to expose a predetermined pattern of a conducting, insulating, or semiconducting material. According to another, the patterned surface is exposed to a plating medium or to metal deposition (for example under vacuum) followed by removal of resist, resulting in a predetermined plated pattern on the surface of the material. In addition to photolithography, x-ray and electron-beam lithography can be used in an analogous fashion. Lithography techniques such as those mentioned above typically require relatively expensive apparatus, and are relatively labor intensive. The techniques require the design and fabrication of chrome masks, access to clean rooms, and other requirements commonly known to those skilled in the art.
Microelectromechanical systems are an area of relatively intensive research. These systems involve the fabrication of microscale structures prepared from silicon, or occasionally from other material such as gallium arsenide, silicon carbide, silicon nitride, metals, glasses, or plastics, by typical integrated circuit industry microfabrication techniques such as photolithography or additive/subtractive processes such as deposition and etching. While interesting systems have been developed, simplification and increased versatility would be advantageous.
Ceramic structures such as borosilicon carbonitride have numerous applications. Ceramics have found extensive use in connection with products to be used in harsh operating conditions such as when exposed to high temperatures, highly oxidative environments, and when exposed to aggressive chemical conditions. Ceramics are also known for their high strength, hardness, low thermal conductivity, and low electrical conductivity.
U.S. Pat. No. 5,698,485 (Brück) describes a process for producing ceramic microstructures from mold inserts structured by using the technique lithographic, galvanoformung, abformung (LIGA), a lithographic structuring method requiring the use of high energy radiation. LIGA requires a high energy radiation sources such as UV radiation, X-rays, or ion beams. Brück also describes structuring simple geometrically shaped PTFE, PC or PMMA mold inserts through machining.
PCT international application number PCT/US98/02573 (Schueller) describes the fabrication of carbon microstructures.
Mat. Res. Innovat. 1999,2,200 (Jungermann, et al.) describes the synthesis of amorphous Si2B2N5C4. Nature 1996, 382, 796 (Riedel, et al.) discloses the synthesis of amorphous silicoboron carbonitride stable up to 2000° C.
These and other techniques for the use of ceramics, including the production of small-scale devices, are useful in some circumstances. However, these techniques typically involve more than a desirable number of fabrication steps, and in many cases it would be advantageous to reduce the cost, and increase versatility, associated with these techniques. Additionally, micromachining is an expensive technique requiring specialty equipment.
Accordingly, it is an object of the invention to provide a technique for forming ceramic solid structures on the micron scale conveniently, inexpensively, and reproducibly.